Multi-trace-element sea surface temperature coral reconstruction for the southern Mozambique Channel reveals teleconnections with the tropical Atlantic
<p>Here we report seasonally resolved sea surface temperatures for the southern Mozambique Channel in the SW Indian Ocean based on multi-trace-element temperature proxy records preserved in two <i>Porites</i> sp. coral cores. Particularly, we assess the suitability of both separate...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-02-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/16/695/2019/bg-16-695-2019.pdf |
| Summary: | <p>Here we report seasonally resolved sea surface temperatures for
the southern Mozambique Channel in the SW Indian Ocean based on multi-trace-element
temperature proxy records preserved in two <i>Porites</i> sp. coral
cores. Particularly, we assess the suitability of both separate and combined
<span class="inline-formula">Sr∕Ca</span> and <span class="inline-formula">Li∕Mg</span> proxies for improved multielement SST
reconstructions. Overall, geochemical records from Europa Island
<i>Porites</i> sp. highlight the potential of <span class="inline-formula">Sr∕Ca</span> and <span class="inline-formula">Li∕Mg</span>
ratios as high-resolution climate proxies but also show significant
differences in their response at this Indian Ocean subtropical reef site. Our
reconstruction from 1970 to 2013 using the <span class="inline-formula">Sr∕Ca</span> SST proxy reveals a
warming trend of <span class="inline-formula">0.58±0.1</span> <span class="inline-formula"><sup>∘</sup></span>C in close agreement with
instrumental data (<span class="inline-formula">0.47±0.07</span> <span class="inline-formula"><sup>∘</sup></span>C) over the last 42 years
(1970–2013). In contrast, the <span class="inline-formula">Li∕Mg</span> showed unrealistically large
warming trends, most probably caused by uncertainties around different uptake
mechanisms of the trace elements Li and Mg and uncertainties in their temperature
calibration. In our study, <span class="inline-formula">Sr∕Ca</span> is superior to <span class="inline-formula">Li∕Mg</span> to
quantify absolute SST and relative changes in SST. However, spatial
correlations between the combined detrended <span class="inline-formula">Sr∕Ca</span> and <span class="inline-formula">Li∕Mg</span>
proxies compared to instrumental SST at Europa revealed robust correlations
with local climate variability in the Mozambique Channel and teleconnections
to regions in the Indian Ocean and southeastern Pacific where surface wind
variability appeared to dominate the underlying pattern of SST variability.
The strongest correlation was found between our Europa SST reconstruction and
instrumental SST records from the northern tropical Atlantic. Only a weak
correlation was found with ENSO, with recent warm anomalies in the
geochemical proxies coinciding with strong El Niño or La Niña. We
identified the Pacific–North American (PNA) atmospheric pattern, which
develops in the Pacific in response to ENSO, and the tropical North Atlantic
SST as the most likely causes of the observed teleconnections with the
Mozambique Channel SST at Europa.</p> |
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| ISSN: | 1726-4170 1726-4189 |